Female Sexual Dysfunction: Definitions, Causes & Potential Treatments

Female sexual dysfunction is age-related, progressive and highly prevalent affecting 30-50 percent of women^(1,2,3). Based on the National Health and Social Life Survey of 1,749 women, 43 percent experienced sexual dysfunction.⁽⁴⁾ U.S. population census data reveal that 9.7 million American women ages 50-74 self-report complaints of diminished vaginal lubrication, pain and discomfort with intercourse, decreased arousal, and difficulty achieving orgasm. Female sexual dysfunction is clearly an important women's health issue that affects the quality of life of many of our female patients.

Until recently, there has been little research or attention that focuses on female sexual function. As a result, our knowledge and understanding of the anatomy and physiology of the female sexual response is quite limited. Based on our understanding of the physiology of the male erectile response, recent advances in modern technology, and recent interest in Women's Health issues, the study of female sexual dysfunction is gradually evolving. Future advances in the evaluation and treatment of female sexual health problems are forthcoming.

The Female Sexual Response Cycle:

Masters and Johnson first characterized the female sexual response in 1966 as consisting of four successive phases; excitement, plateau, orgasmic and resolution phases⁽⁵⁾. In 1979, Kaplan proposed the aspect of "desire", and the three-phase model, consisting of desire, arousal, and orgasm⁽⁶⁾. However, in October 1998, a consensus panel made up of a multidisciplinary team treating female sexual dysfunction met to create new a new classification system that all professionals treating Female Sexual dysfunction can use.

1998 AFUD Consensus Panel Classifications & Definitions of Female Sexual Dysfunction

• Hypoactive Sexual Desire Disorder: persistent or recurring deficiency (or absence) of sexual fantasies/thoughts, and/or receptivity to, sexual activity, which causes personal distress.
• Sexual Aversion Disorder: persistent or recurring phobic aversion to, and avoidance of sexual contact with a sexual partner, which causes personal distress. Sexual Aversion Disorder is generally a psychologically or emotionally based problem that can result for a variety of reasons such as physical or sexual abuse, or childhood trauma, etc.
• Hypoactive Sexual Desire Disorder may result from psychological/emotional factors or be secondary to medical problems such as hormone deficiencies, and medical or surgical interventions. Any disruption of the female hormonal system caused by natural menopause, surgically or medically induced menopause, or endocrine disorders can result in inhibited sexual desire.
• Sexual Arousal Disorder: persistent or recurring inability to attain, or maintain sufficient sexual excitement causing personal distress. It may be experienced as lack of subjective excitement or lack of genial (lubrication/swelling) or other somatic responses.

Disorders of arousal include, but are not limited to, lack of or diminished vaginal lubrication, decreased clitoral and labial sensation, decreased clitoral and labial engorgement or lack of vaginal smooth muscle relaxation.

These conditions may occur secondary to psychological factors, however often there is a medical/physiologic basis such as diminished vaginal/clitoral blood flow, prior pelvic trauma, pelvic surgery, medications (i.e. SSRI) ^(7,8)

• Orgasmic Disorder: persistent or recurrent difficulty, delay in, or absence of attaining orgasm following sufficient sexual stimulation and arousal, and causes personal distress.

This may be a primary (never achieved orgasm) or a secondary condition, as a result of surgery, trauma, or hormone deficiencies. Primary anorgasmia can be secondary to emotional trauma or sexual abuse, however medical/physical factors can certainly contribute to the problem.

• Sexual Pain Disorders:
  • Dyspareunia: recurrent or persistent genital pain associated with sexual intercourse
  • Vaginismus: recurrent or persistent involuntary spasm of the musculature of the outer third the vagina that interferes with vaginal penetration, which causes personal distress.
• Other sexual pain disorders: Recurrent or persistent genital pain induced by non-coital sexual stimulation. Dyspareunia can develop secondary to medical problems such as vestibulitis, vaginal atrophy, or vaginal infection can be either physiologically or psychologically based, or a combination of the two. Vaginismus usually develops as a conditioned response to painful penetration, or secondary to psychological/emotional factors.

Role of Hormones in Female Sexual Function:

Hormones play a significant role in regulating female sexual function. In animal models, estrogen administration results in expanded touch receptor zones, suggesting that estrogen effects sensation. In post-menopausal women, estrogen replacement restores clitoral and vaginal vibration and sensation to levels close to those of pre-menopausal women⁽¹⁵⁾. Estrogens also have protective effects which result in increased blood flow to the vagina and clitoris ^(15,16). This helps to maintain female sexual response over time.

With aging and menopause, and the decreasing estrogen levels, a majority of women experience some degree of change in sexual function. Common sexual complaints include loss of desire, decreased frequency of sexual activity, painful intercourse, diminished sexual responsiveness, difficulty achieving orgasm, and decreased genital sensation.

Masters and Johnson first published their findings of the physical changes occurring in menopausal women that related to sexual function in 1966. We have since learned that symptoms of low lubrication and poor sensation are in part secondary to declining estrogen levels and that there is a direct correlation between the presence of sexual complaints and low levels of estrogen⁽¹⁵⁾. Symptoms markedly improve with estrogen replacement.

Low testosterone levels are also associated with a decline in sexual arousal, genital sensation, libido, and orgasm. There have been studies that have documented improvements in women's desire when treated with 100 mg testosterone pellets ^(17,18). At this time, there are not Food and Drug Administration (FDA) approved testosterone preparations for women; however clinical studies are underway assessing the potential benefits of testosterone for the treatment of female sexual dysfunction.

Causes of Female Sexual Dysfunction:

Vascular

High blood pressure, high cholesterol levels, diabetes, smoking, and heart disease are associated with sexual complaints in men and women. Any traumatic injury to the genitals or pelvic region, such as pelvic fractures, blunt trauma, surgical disruption, extensive bike riding, for instance, can result in diminished vaginal and clitoral blood flow and complaints of sexual dysfunction. Although, other underlying conditions, either psychological or physiologic may also manifest as decreased vaginal and clitoral engorgement, blood flow, or vascular insufficiency is one causal factor that should be considered.

Neurological

The same neurological disorders that cause erectile dysfunction in men can also cause sexual dysfunction in women. Spinal cord injury or disease of the central or peripheral nervous system, including diabetes, can result in female sexual dysfunction. Women with spinal cord injury have significantly more difficulty achieving orgasm than able-bodied women ⁽²¹⁾. The effects of specific spinal cord injuries on female sexual response is being investigated, and will hopefully lead to improved understanding of the neurological pieces of orgasm and arousal in normal women.

Hormonal/Endocrine

Dysfunction of the hypothalamic/pituitary axis, surgical or medical castration, natural menopause, premature ovarian failure, and chronic birth control pills, are the most common causes of hormonally based female sexual dysfunction. The most common complaints in this category are decreased desire and libido, vaginal dryness, and lack of sexual arousal.

Psychogenic

In women, despite the presence or absence of organic disease, emotional and relational issues significantly affect sexual arousal. Issues such as self-esteem, body image, her relationship with her partner, and her ability to communicate her sexual needs with her partner, all impact sexual function. In addition, psychological disorders such as depression, obsessive-compulsive disorder, anxiety disorder, etc., are associated with female sexual dysfunction. Medications used to treat depression can also significantly affect the female sexual response. The most frequently used medications for uncomplicated depression are the Seratonin Re-uptake Inhibitors. Women receiving these medications often complain of decreased sexual interest.

Treatment Options:

Treatment of female sexual dysfunction is gradually evolving as more clinical and basic science studies are dedicated to evaluating the problem. Aside from hormone replacement therapy, medical management of female sexual dysfunction remains in early experimental phases. Nonetheless, it is crucial to understand that not all female sexual complaints are psychological and that there are possible therapeutic options.

Studies are in progress accessing the effects of vasoactive substances on the female sexual response. Aside from hormone replacement therapy, all medications listed below, while useful in the treatment of male erectile dysfunction, are still in experimental phases for use in women.

• Estrogen Replacement Therapy: This treatment is indicated in menopausal women (either spontaneous or surgical). Aside from reliving hot flashes, preventing osteoporosis, and lowering risk of heart disease, estrogen replacement results in improved clitoral sensitivity, increased libido, and decreased pain during intercourse. Local or topical estrogen application relieves symptoms of vaginal dryness, burning, and urinary frequency and urgency. In menopausal women, or oophorectomized women, complaints of vaginal irritation, pain or dryness, can be relieved with topical estrogen cream. A vaginal estradiol ring (Estring) is now available that delivers low-dose estrogen locally, which may benefit breast cancer patients and other women unable to take oral or transdermal estrogen ⁽²⁵⁾.
• Methyl Testosterone: This treatment is often used in combination with estrogen in menopausal women, for symptoms of inhibited desire, dyspareunia, or lack of vaginal lubrication. There are conflicting reports regarding the benefit of methyltestosterone and/or testosterone cream for the treatment of inhibited desire and/or vaginismus in pre-menopausal women. Potential benefits of this therapy include increased clitoral sensitivity, increased vaginal lubrication, increased libido, and heightened arousal. Potential side effects of testosterone administration, either topical or oral, include weight gain, clitoral enlargement, increased facial hair, and high cholesterol.
• Sildenafil: This medication serves to increase relaxation of clitoral and vaginal smooth muscle and blood flow to the genital area⁽⁷⁾. Sildenafil may prove useful alone or possibly in combination with other vasoactive substances for the treatment of female sexual arousal disorder. Clinical studies evaluating the safety and efficacy of this medication in women with sexual arousal disorder are in progress. Several studies are already published demonstrating the efficacy of sildenafil for the treatment of female sexual dysfunction secondary to SSRI use^(20,23) Another study was recently published describing subjective effects of sildenafil in a population of post-menopausal women. ⁽²⁶⁾
• L-arginine: This amino acid functions as a precursor to the formation of nitric oxide, which mediates relaxation of vascular and non-vascular smooth muscle. L-arginine has not been used in clinical trials in women; however preliminary studies in men appear promising. The standard dose is 1500mg/day.
• Phentolamine (Vasomax)): Currently available in an oral preparation, this drug causes vascular smooth muscle relaxation and increases blood flow to the genital area. This drug has been studied in male patients for the treatment of erectile dysfunction. A pilot study in menopausal women with sexual dysfunction demonstrated enhanced vaginal blood flow and improved subjective arousal with the medication.
• Apomorphine: Initially designed as an antiparkinsonian agent, this short-acting medication facilitates erectile responses in both normal males and males with psychogenic erectile dysfunction, as well as males with medical impotence. Data from pilot studies in men suggests that dopamine may be involved in the mediation of sexual desire as well as arousal. The physiologic effects of this drug have not been tested in women with sexual dysfunction, but it may prove useful either alone or in combination with vasoactive medications. It will be delivered sublingually.

The ideal approach to female sexual dysfunction is a collaborative effort between therapists and physicians. This should include a complete medical, and psychosocial evaluation, as well as inclusion of the partner or spouse in the evaluation and treatment process. Although there are significant anatomic and embryologic parallels between men and women, the multifaceted nature of female sexual dysfunction is clearly distinct from that of the male.

The context in which a woman experiences her sexuality is equally if not more important than the physiologic outcome she experiences, and these issues need to be determined prior to beginning medical therapies or attempting to determine treatment efficacies. Whether Viagra or other vasoactive agents are demonstrated to be predictably effective in women remains to be seen. At very least, discussions such as this will hopefully lead to heightened interest and awareness as well as more clinical and basic science research in this area.

by Laura Berman, Ph.D. and Jennifer Berman, M.D.

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